U.S. patent application number 12/664676 was filed with the patent office on 2010-07-15 for process for removing fluorinated compounds from an aqueous phase originating from the preparation of fluoropolymers.
Invention is credited to Klaus Hintzer, Michael Jurgens, Harald Kaspar, Kai H. Lochhaas, Andreas R. Maurer, Werner Schwertfeger, Tilman C. Zipplies.
Application Number | 20100179293 12/664676 |
Document ID | / |
Family ID | 38352792 |
Filed Date | 2010-07-15 |
United States Patent
Application |
20100179293 |
Kind Code |
A1 |
Hintzer; Klaus ; et
al. |
July 15, 2010 |
PROCESS FOR REMOVING FLUORINATED COMPOUNDS FROM AN AQUEOUS PHASE
ORIGINATING FROM THE PREPARATION OF FLUOROPOLYMERS
Abstract
A process of removing fluorinated compounds from an aqueous
phase originating from the preparation of fluoropolymers said
process comprising the use of polycationic polymers.
Inventors: |
Hintzer; Klaus; ( Kastl,
DE) ; Jurgens; Michael; (Neuoetting, DE) ;
Maurer; Andreas R.; (Langenneufnach, DE) ;
Schwertfeger; Werner; (Langgons, DE) ; Zipplies;
Tilman C.; (Burghausen, DE) ; Lochhaas; Kai H.;
(Neuoetting, DE) ; Kaspar; Harald; (Burgkirchen,
DE) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Family ID: |
38352792 |
Appl. No.: |
12/664676 |
Filed: |
May 8, 2008 |
PCT Filed: |
May 8, 2008 |
PCT NO: |
PCT/US08/62976 |
371 Date: |
December 15, 2009 |
Current U.S.
Class: |
526/255 |
Current CPC
Class: |
C08F 6/22 20130101; C08F
114/18 20130101; C08F 214/18 20130101; C08F 6/16 20130101; C08F
6/16 20130101; C08F 6/22 20130101; C08F 14/18 20130101; C08F 2/10
20130101; C08F 14/18 20130101; C08L 27/12 20130101; C08L 27/12
20130101 |
Class at
Publication: |
526/255 |
International
Class: |
C08F 114/26 20060101
C08F114/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2007 |
GB |
0712191.6 |
Claims
1. A process for reducing the amount of fluorinated compounds in an
aqueous phase, the process comprising a) adding to the aqueous
phase one or more polycationic polymers or precursor polymers
thereof to cause at least partial precipitation of fluorinated
compounds, and b) adding to the aqueous phase one or more
polyanionic polymers.
2. A process for reducing the amount of fluorinated compounds in an
aqueous phase, the process comprising adding to the aqueous phase
one or more polycationic polymers or precursor polymers thereof to
cause at least partial precipitation of fluorinated compounds, and
wherein the aqueous phase contains at least 20 ppm of a fluorinated
emulsifier.
3. The process according to claim 1 wherein b) is carried out after
or simultaneously with a).
4. The process according to claim 1 wherein the aqueous phase
contains at least 20 ppm of a fluorinated emulsifier.
5. The process according to claim 1, wherein the polycationic
polymers or precursor polymers thereof have a molecular weight
(number average) of at least 5,000 g/mol.
6. The process according to claim 1 wherein the polyanionic
polymers have a molecular weight (number average) of at least 5,000
g/mol.
7. The process according to claim 1 wherein the fluorinated
compounds are amorphous fluoropolymers.
8. The process according to claim 1 wherein the fluorinated
compounds comprise repeating units derived from monomers selected
from the group consisting of vinylidene fluoride (VDF), ethylene
(E), propylene (P), perfluoro methyl vinyl ether (PMVE) or
perfluoro propyl vinyl ether (PPVE) or a combination thereof.
9. The process according to claim 1 wherein the aqueous phase
comprises less than 10% wt. of solids.
10. The process according to claim 1 wherein the aqueous phase
contains at least 50 .mu.g per g of aqueous phase of anions
selected from the group consisting of chloride, nitrate, phosphate,
hydrogen phosphate, sulphate, hydrogensulfate, monocarboxylate,
dicarboxylate, sulfonate, phosphonate or a combination thereof.
11. The process according to claim 1, wherein the aqueous phase has
been obtained after salt-induced coagulation of the
fluoropolymers.
12. The process according to claim 1 claims further comprising
acidifying the precipitate and recovering one or more fluorinated
compounds from the precipitate by extraction of distillation.
13. The process according to claim 2, wherein the polycationic
polymers or precursor polymers thereof have a molecular weight
(number average) of at least 5,000 g/mol.
14. The process according to claim 2, wherein the polyanionic
polymers have a molecular weight (number average) of at least 5,000
g/mol.
15. The process according to claim 2, wherein the fluorinated
compounds are amorphous fluoropolymers.
16. The process according to claim 2, wherein the fluorinated
compounds comprise repeating units derived from monomers selected
from the group consisting of vinylidene fluoride (VDF), ethylene
(E), propylene (P), perfluoro methyl vinyl ether (PMVE) or
perfluoro propyl vinyl ether (PPVE) or a combination thereof.
17. The process according to claim 2, wherein the aqueous phase
comprises less than 10% wt. of solids.
18. The process according to claim 2, wherein the aqueous phase
contains at least 50 .mu.g per g of aqueous phase of anions
selected from the group consisting of chloride, nitrate, phosphate,
hydrogen phosphate, sulphate, hydrogensulfate, monocarboxylate,
dicarboxylate, sulfonate, phosphonate or a combination thereof.
19. The process according to claim 2, wherein the aqueous phase has
been obtained after salt-induced coagulation of the
fluoropolymers.
20. The process according to claim 2, claims further comprising
acidifying the precipitate and recovering one or more fluorinated
compounds from the precipitate by extraction of distillation.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a process of removing
fluorinated compounds, in particular partially fluorinated
polymers, such as, elastomers, from an aqueous phase, preferably
waste water.
BACKGROUND OF THE INVENTION
[0002] Fluoropolymers, that is, polymers having a fluorinated
backbone, have long been known and used in various applications
because of their desirable properties such as heat resistance,
chemical resistance, weatherability, UV-stability etc. Various
fluoropolymers are for example described in "Modern
Fluoropolymers", edited by John Scheirs (ed), Wiley Science 1997.
The fluoropolymers may have a partially fluorinated backbone,
generally at least 40% by weight fluorinated, or a fully
fluorinated backbone. Particular examples of fluoropolymers include
polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene
(TFE) and hexafluoropropylene (HFP) (so-called FEP polymers),
fluoropolymers containing perfluoroalkoxy copolymers (so-called PFA
polymers), ethylene-tetrafluoroethylene copolymers (ETFE),
terpolymers of TFE, HFP and vinylidene fluoride (so-called THV
polymers) and polyvinylidene fluoride polymers (PVDF).
Fluoropolymers also include amorphous fluoropolymers, which upon
curing become elastomeric properties, such as so-called FKM
polymers or FFKM polymers.
[0003] A frequently used method for producing fluoropolymers
involves aqueous emulsion polymerization. This method generally
involves the use of fluorinated emulsifiers. Perfluorinated
carboxylic acids, such as perfluorooctanoic acids and salts
thereof, in particular ammonium perfluorooctanoic acid (APFO), are
commonly used for this purpose. The fluoropolymers are typically
separated from the aqueous reaction mixture by coagulating and
removing the aqueous phase. The obtained aqueous phase usually
contains non-coagulated fluoropolymer particles and fluorinated
emulsifiers. The fluorinated emulsifiers stabilize the
non-coagulated fluoropolymer particles and form stable colloidal
dispersions in which the particles are finely dispersed. Typically,
these colloidal dispersions cannot be effectively treated by common
filtration techniques. Therefore, known methods of treating
fluoropolymer waste water typically employ anion-exchange processes
and at least one further separation technique. Anion-exchange
resins are used to separate the fluorinated emulsifiers from the
waste water. Removing the fluorinated emulsifiers by anion-exchange
resins leads to destabilization and precipitation of the
fluoropolymer particles. Precipitated particles may clog the anion
exchange resin and reduce its capacity. Therefore, the waste water
is typically stabilized, for example, by adding non-ionic
surfactants. Non-ionic surfactant and fluoropolymer particles have
to be removed separately after the ion-exchange step.
[0004] In an alternative approach fluoropolymers may be prepared in
aqueous media without using fluorinated emulsifiers. Such a method
has been described in, for example, WO2007/038561. However,
although no fluorinated emulsifiers were used, fluorinated low
molecular weight oligomers were generated in situ. These oligomers
were found to behave like fluorinated emulsifiers in that they were
capable of stabilizing non-coagulated fluoropolymer particles by
forming stable colloidal dispersions. Like the above-cited prior
art, WO2007/038561 also suggests to treat the waste water by
anion-exchange chromatography for removing the oligomers.
[0005] Although these methods may lead to an appropriate removal of
fluorinated compounds from waste water, they are cost-intensive.
First of all, ion-exchange technology is comparatively expensive.
Additionally, the above-described methods do not only require
ion-exchange technology but also at least another different
separation technique. This increases maintenance and equipment
costs.
[0006] Furthermore, it has been found that the presence of
inorganic or organic salts may reduce the capacity of the anion
exchange resins rendering the removal of fluorinated emulsifiers
from waste water containing high amounts of salts less efficient.
High amounts of salts are typically present when the fluoropolymers
are separated from aqueous dispersions by salt-induced coagulation.
In this type of coagulation the aqueous fluoropolymer dispersions
are destabilised by increasing the ionic strength of the aqueous
phase by adding inorganic or organic salts until the fluoropolymers
coagulate.
[0007] This reduced efficacy of anion exchange resins in the
presence of organic or inorganic salts has been observed to be
particularly pronounced in the preparation of partially fluorinated
fluoropolymers, such as, elastomers. In such processes partially
fluorinated oligomers having anionic end groups may be formed as
by-products. These oligomers tend to bind less strongly to
anion-exchange resins than perfluorinated emulsifiers and are
easily replaced by competing salt anions, reducing the
effectiveness of the anion exchange technology.
SUMMARY OF THE INVENTION
[0008] There is still a need for providing a cost-effective method
of removing fluorinated compounds from an aqueous phase.
Additionally, there is still a need for a method of reducing the
amount of fluorinated compounds in an aqueous phase that
effectively simultaneously reduces fluorinated low molecular weight
oligomers and/or fluorinated emulsifiers and fluoropolymer
particles in a single separation operation. Furthermore, there is
still a need for a simple and robust method for removing
fluorinated compounds from the waste water of the preparation of
partially fluorinated fluoropolymers, such as elastomers, with or
without using fluorinated emulsifiers. In particularly, there is a
need for a simple method of removing fluorinated materials from an
aqueous phase containing rather substantial amounts of organic or
inorganic salts, such as, for example, waste water obtained from
the salt-induced coagulation of fluoropolymers.
[0009] It has now been found that fluorinated compounds can be
efficiently removed by precipitation using at least one
polycationic polymer or precursor thereof and without the need of
additional ion-exchange chromatography.
[0010] It has also been found that even fluorinated emulsifiers can
be sufficiently removed by precipitation using a polycationic
polymer or precursor thereof.
[0011] Precipitation can be improved by further adding at least one
polyanionic polymer.
[0012] Therefore, there is provided a process of reducing the
amount of fluorinated compounds in an aqueous phase, the process
comprising
a) adding to the aqueous phase one or more polycationic polymers or
precursor polymers thereof to cause at least partial precipitation
of fluorinated compounds and b) adding to the aqueous phase one or
more polyanionic polymers.
[0013] There is also provided a process of reducing the amount of
fluorinated compounds in an aqueous phase, the process comprising
adding to the aqueous phase one or more polycationic polymers or
precursor polymers thereof to cause at least partial precipitation
of fluorinated compounds, wherein the aqueous phase contains at
least 20 ppm of a fluorinated emulsifier.
[0014] An advantage of the processes provided herein is that
efficient removal of fluorinated compounds can be achieved using a
single separation technique instead of multiple different ones.
[0015] A further advantage is that cost-intensive column technology
is not required because the same or even improved efficacy in
removing fluorinated compounds is achieved.
[0016] Yet another advantage is that no additional surfactants, in
particular non-ionic surfactants have to be added to the aqueous
phase reducing the total organic carbon content (TOC) of the waste
water.
[0017] A further advantage of the processes can be seen in that the
amount of fluoropolymer particles, fluorinated molecular weight
oligomers, and if present fluorinated emulsifiers, may be reduced
simultaneously.
[0018] Additionally, the processes allow for the recovery of at
least some of the fluorinated compounds after their separation from
the aqueous phase.
[0019] Desirably, the processes can be applied with comparable
efficiency equally to aqueous phases containing high quantities or
low amounts of fluorinated compounds.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Typically, the aqueous phase is generated in the production
of fluoropolymers, such as, the preparation and/or the purification
and work-up of fluoropolymers.
[0021] Preferably, the aqueous phase originates from the production
of fluoropolymers using an aqueous medium, such as, aqueous
emulsion or suspension polymerization. More preferably, the aqueous
phase is obtained after separating fluoropolymers from aqueous
dispersions. Preferably, this is achieved by salt-induced
coagulation, that is, coagulation by increasing the ionic strength
of the dispersion through addition of salts to the dispersion.
Salt-induced coagulation is typically carried out by adding low
molecular weight salts (typically salts having a molecular weight
of less than 800 g/mol or less than 500 g/mol) to the dispersion.
These salts may be organic or inorganic. The aqueous phase may
contain at least about 5, or at least about 50, or at least about
150, or at least about 500 .mu.g per g waste water of one or more
organic and/or inorganic salt anions. Typical inorganic salt anions
include chloride, bromide, iodide, nitrate, phosphate, hydrogen
phosphate, sulphate, hydrogen sulphate, sulfides, hydrogen sulfides
or mixtures and combinations thereof.
[0022] The aqueous phase may also include at least about 5, or at
least about 50 or at least about 500 .mu.g per g of aqueous phase
of non-fluorinated organic acid anions. Typical organic anions
include mono-, di- or polysulfonates, mono-, di- or
polyphosphonates, mono- di- or polycarboxylates, such as for
example oxalates, citrates, formiates, acetates, lactates,
malonates or combinations thereof.
[0023] Examples of typical salts include but are not limited to
magnesium chloride, magnesium sulphate, sodium chloride, iron
chloride, iron sulphate, ammonium nitrate, ammonium sulphate,
aluminium chloride, aluminium hydroxide, acetates, oxalates,
citrates, formiates, lactates, etc.
[0024] The aqueous phase may also be obtained after washing the
fluoropolymers, obtained after washing reaction vessels used in the
polymerization or obtained from treatment of exhausts from the
fluoromonomer polymerization in scrubbers.
[0025] Preferably, the aqueous phase is waste water, such as, for
example, waste water collected during polymer preparation and
work-up of fluoropolymers. Therefore, the aqueous phase may contain
low amounts of fluoropolymers or solids, such as, up to about 10%
or up to about 5% or up to about 1% by weight based on the weight
of the aqueous phase. The aqueous phase may further contain at
least 1 ppm of a fluorinated emulsifier. The aqueous phase may
contain at least 20 ppm, at least 50 ppm, at least 150, at least
500 ppm or at least 1,000 ppm of a fluorinated emulsifier. The
fluorinated emulsifiers may be those that have been added prior or
during the polymerisation or those that may be formed in situ
during the polymerization.
[0026] Unless expressed otherwise, any amounts given in ppm or %
wt. are based on the weight of the aqueous phase.
[0027] Preferably, the aqueous phase is obtained after salt-induced
coagulation of the fluoropolymers.
[0028] In one embodiment, the aqueous phase is waste water that has
not been submitted to an anion-exchange resin.
Fluoropolymers
[0029] The fluoropolymers comprise repeating units derived from
monomers, such as fluorinated olefins. The polymers may comprise at
least 10 or at least 20 repeating units.
[0030] The fluoropolymers may be obtained by polymerization or
copolymerization of fluorinated olefins, such as for example
tetrafluoroethylene (TFE), hexafluoropropylene (HFP), vinylidene
fluoride (VDF), chlorotrifluoroethylene (CTFE), perfluorinated or
partially fluorinated alkylvinylether, such as for example
perfluoromethylvinyl ether (PMVE), perfluoropropylvinylether,
perfluoroisopropylvinlyether, perfluorinated or partially
fluorinated allylether or vinyl ether, such as for example
compounds of the general formula
CF.sub.2.dbd.CF--(CF.sub.2).sub.n--O--R.sub.F
with n being 0 or 1 and R.sub.F being a C.sub.1-C.sub.10
(perfluorinated, partially fluorinated or non fluorinated) alkyl or
alkyloxy residue with 1 to 5 oxygen atoms, such as, for example,
CF.sub.2.dbd.CF--O--(CF.sub.2).sub.3OCF.sub.3,
CF.sub.2.dbd.CFO(CF.sub.2).sub.2OCF.sub.3 etc, or fluorinated
olefins further containing one or more polar group selected from
the groups --CN, --Br, --I, --SO.sub.2F, --COOR, --SO.sub.3.sup.-,
--COO.sup.- or mixtures thereof.
[0031] Non-fluorinated olefins, such as for example ethylene (E) or
propylene (P), may also be used as comonomers.
[0032] Preferably, the fluoropolymers comprise repeating units
derived from VDF or they may comprise repeating units derived from
monomers selected from:
VDF, HFP and TFE;
[0033] VDF, HFP, TFE and a non fluorinated olefin such as ethylene
(E) or propylene (P);
TFE, VDF and E or P;
VDF, HFP, TFE and PMVE;
VDF, HFP, TFE, PMVE and E or P.
[0034] These polymers may further contain one or more units derived
from fluorinated or partially fluorinated olefins containing one or
more curable moieties, for example, polar group, such as, --CN,
--Br, --I, --SO.sub.2F, --COOR, --SO.sub.3.sup.-, --COO.sup.- or
mixtures thereof.
[0035] The fluoropolymers may be partially fluorinated. This means
the fluoropolymers contain repeating units comprising one or more
--CH.sub.2-- and/or --CFH-- moieties.
[0036] The fluoropolymers may be amorphous. Amorphous
fluoropolymers do not have a distinct melting point. Amorphous,
partially fluorinated fluoropolymers are generally used in the
preparation of fluoroelastomers. Although fluoroelastomers obtain
their elastomeric properties after curing, polymers used in the
preparation of elastomers are also referred to as elastomers.
Therefore, the waste water may also be waste water obtained from
the preparation of elastomers, which are amorphous, partially
fluorinated fluoropolymers.
[0037] The fluoropolymers may have a molecular weight (number
average, M.sub.n) of greater than about 5,000 g/mol. The molecular
weight can be determined by standard methods, for example gel
permeation chromatography).
Fluorinated Emulsifiers
[0038] The aqueous phase may contain one or more fluorinated
emulsifiers. Fluorinated emulsifiers as used herein are low
molecular weight organic compound having one or more --COO.sup.-,
--OSO.sub.4.sup.- or --SO.sub.3.sup.- groups and having a molecular
weight (as far as the anionic part of the molecule is concerned,
that is, without the molecular weight of the counterions, such as,
cations or H+) of less than about 1000 g/mol, preferably less than
500 g/mol.
[0039] Typically, the fluorinated emulsifiers correspond to the
formula:
(Y--R.sub.f--Z)M (I)
wherein Y represents Cl or F; R.sub.f represents a linear or
branched perfluorinated alkylene having 4 to 10 carbon atoms; Z
represents COO.sup.-, OSO.sub.3.sup.- or SO.sub.3.sup.-; M
represents a monovalent cation, for example, an alkali metal ion or
an ammonium ion.
[0040] Representative examples of fluorinated emulsifiers according
to above formula (I) include perfluoroalkanoic acids and salts
thereof such as perfluorooctanoic acid and its salts, in particular
ammonium salts, such as ammonium perfluoro octanoic acid
(APFO).
[0041] Other examples of emulsifiers include perfluorinated or
partially fluorinated carboxylic acids or salts thereof
corresponding to the general formula:
[R.sub.f--O-L-COO.sup.-].sub.iX.sup.i+ (II)
wherein L represents a linear fully or partially fluorinated
alkylene group, R.sub.f represents a linear fully or partially
fluorinated aliphatic group or a linear fully or partially
fluorinated aliphatic group interrupted with one or more oxygen
atoms, X.sup.i+ represents a cation having the valence i and i is
1, 2 or 3. Examples of cations include H.sup.+, ammonium,
monovalent metal cations, divalent metal cations and trivalent
cations. Typical cations are H.sup.+K.sup.+, Na.sup.+ and
NH.sub.4.sup.+.
[0042] Examples for emulsifiers according to formula (II) are
described in greater detail in US Pat. Appl. 2007/0015937 by
Hintzer et al.
[0043] Specific examples of compounds according to formula (II)
include the following:
R.sub.f--O--CHF--COOH:
[0044] C.sub.3F.sub.7--O--CHF--COOH,
CF.sub.3--O--CF.sub.2CF.sub.2--CF.sub.2--O--CHF--COOH,
CF.sub.3CF.sub.2CF.sub.2--O--CF.sub.2CF.sub.2--CF.sub.2--O--CHF--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--O--CHF--COOH,
CF.sub.3--O--CF.sub.2--O--CF.sub.2--CF.sub.2--O--CHF--COOH,
CF.sub.3--(O--CF.sub.2).sub.2--O--CF.sub.2--CF.sub.2--O--CHF--COOH,
CF.sub.3--(O--CF.sub.2).sub.3--O--CF.sub.2--CF.sub.2--O--CHF--COOH;
R.sub.f--O--CHF--CF.sub.2--COOH:
[0045] CF.sub.3--O--CHF--CF.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--O--CHF--CF.sub.2--COOH,
CF.sub.3--CF.sub.2--O--CHF--CF.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CHF--CF.sub.2--COOH,
CF.sub.3--O--CF.sub.2--O--CF.sub.2--CF.sub.2--O--CHF--CF.sub.2--COOH,
CF.sub.3--(O--CF.sub.2).sub.2--O--CF.sub.2--CF.sub.2--O--CHF--CF.sub.2--C-
OOH,
CF.sub.3--(O--CF.sub.2).sub.3--O--CF.sub.2--CF.sub.2--O--CHF--CF.sub.-
2--COOH;
R.sub.f--O--CF.sub.2--CHFCOOH:
[0046] CF.sub.3--O--CF.sub.2--CHF--COOH,
C.sub.3F.sub.7--O--CF.sub.2--CHF--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CF.sub.2--CHF--COOH,
CF.sub.3--O--CF.sub.2--O--CF.sub.2--CF.sub.2--O--CF.sub.2--CHF--COOH,
CF.sub.3--(O--CF.sub.2).sub.2--O--CF.sub.2--CF.sub.2--O--CF.sub.2--CHF--C-
OOH,
CF.sub.3--(O--CF.sub.2).sub.3--O--CF.sub.2--CF.sub.2--O--CF.sub.2--CH-
F--COOH;
R.sub.f--O--CF.sub.2--CHF--CF.sub.2COOH:
[0047] CF.sub.3--O--CF.sub.2--CHF--CF.sub.2--COOH,
C.sub.2F.sub.5--O--CF.sub.2--CHF--CF.sub.2--COOH,
C.sub.3F.sub.7--O--CF.sub.2--CHF--CF.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CF.sub.2--CHF--CF.sub.2--CO-
OH,
CF.sub.3--O--CF.sub.2--O--CF.sub.2--CF.sub.2--O--CF.sub.2--CHF--CF.sub-
.2--COOH,
CF.sub.3--(O--CF.sub.2).sub.2--O--CF.sub.2--CF.sub.2--O--CF.sub.-
2--CHF--CF.sub.2--COOH,
CF.sub.3--(O--CF.sub.2).sub.3--O--CF.sub.2--CF.sub.2--O--CF.sub.2--CHF--C-
F.sub.2--COOH;
R.sub.f--(O).sub.m--CHF--CF.sub.2--O--(CH.sub.2).sub.n--COOH n=1, 2
or 3; m=0 or 1:
[0048] CF.sub.3--O--CHF--CF.sub.2--O--CH.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CHF--CF.sub.2--O--CH.sub.2--
-COOH, C.sub.3F.sub.7--O--CHF--CF.sub.2--O--CH.sub.2--COOH,
C.sub.3F.sub.7--O--CHF--CF.sub.2--O--CH.sub.2--CH.sub.2--COOH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--O--CHF--CF.sub.2--OCH.sub.2COOH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CHF--CF.sub.2--OCH.su-
b.2COOH, C.sub.3F.sub.7--O--CF.sub.2--CHF--CF.sub.2--OCH.sub.2COOH,
CF.sub.3--CHF--CF.sub.2--O--CH.sub.2COOH,
C.sub.3F.sub.7--CF.sub.2--CHF--CF.sub.2--OCH.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--O--CH.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CF.sub.2--CF.sub.2--O--CH.s-
ub.2--COOH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--O--CH.sub.2--COOH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--O--CH.sub.2--CH.sub.2--COOH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--O--CF.sub.2--CF.sub.2--OCH.sub.2CO-
OH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CF.sub.2--CF.sub.2-
--OCH.sub.2COOH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--CF.sub.2--OCH.sub.2COOH,
C.sub.4F.sub.9--O--CH.sub.2--COOH,
C.sub.4F.sub.9--O--CH.sub.2--CH.sub.2--COOH,
C.sub.3F.sub.7--O--CH.sub.2COOH, C.sub.6F.sub.13--OCH.sub.2--COOH,
R.sub.f--O--CF.sub.2--CF.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--COOH,
C.sub.2F.sub.5--O--CF.sub.2--CF.sub.2--COOH,
C.sub.3F.sub.7--O--CF.sub.2--CF.sub.2--COOH,
C.sub.4F.sub.9--O--CF.sub.2--CF.sub.2--COOH,
R.sub.f--(O--CF.sub.2).sub.u--O--CF.sub.2--COOH:
[0049] CF.sub.3--(O--CF.sub.2).sub.3--O--CF.sub.2--COOH,
CF.sub.3--(O--CF.sub.2).sub.2--O--CF.sub.2--COOH,
CF.sub.3--(O--CF.sub.2).sub.1--O--CF.sub.2--COOH;
R.sub.f--(O--CF.sub.2--CF.sub.2).sub.k--O--CF.sub.2--COOH with k
being 1, 2 or 3:
[0050] CF.sub.3--(O--CF.sub.2--CF.sub.2).sub.1--O--CF.sub.2--COOH,
C.sub.2F.sub.5--(O--CF.sub.2--CF.sub.2).sub.1--O--CF.sub.2--COOH,
C.sub.3F.sub.7--(O--CF.sub.2--CF.sub.2).sub.1--O--CF.sub.2--COOH,
C.sub.4F.sub.9--(O--CF.sub.2--CF.sub.2).sub.1--O--CF.sub.2--COOH,
C.sub.2F.sub.5--(O--CF.sub.2--CF.sub.2).sub.2--O--CF.sub.2--COOH,
CF.sub.3--(O--CF.sub.2--CF.sub.2).sub.2--O--CF.sub.2--COOH,
C.sub.3F.sub.7--(O--CF.sub.2--CF.sub.2).sub.2--O--CF.sub.2--COOH,
C.sub.4F.sub.9--(O--CF.sub.2--CF.sub.2).sub.2--O--CF.sub.2--COOH;
R.sub.f--O--CF.sub.2--COOH:
[0051] C.sub.3F.sub.7--O--CF.sub.2--COOH,
CF.sub.3--O--CF.sub.2--CF.sub.2--CF.sub.2--O--CF.sub.2--COOH;
CF.sub.3--CHF--O--(CF.sub.2).sub.o--COOH with o being an integer of
1, 2, 3, 4, 5 or 6:
[0052] CF.sub.3CFH--O--(CF.sub.2).sub.3--COOH,
CF.sub.3CFH--O--(CF.sub.2).sub.5--COOH
CF.sub.3--CF.sub.2--O--(CF.sub.2).sub.o--COOH:
[0053] CF.sub.3--CF.sub.2--O--(CF.sub.2).sub.3COOH,
CF.sub.3--CF.sub.2--O--(CF.sub.2).sub.5COOH
[0054] Yet further examples of fluorinated emulsifiers correspond
to the general formula (III):
M'(Z'--R.sub.f--Z)M (III)
wherein R.sub.f represents a linear or branched perfluorinated or
partially fluorinated alkylene having 4 to 10 carbon atoms; Z and
Z' represent independently from each other COO.sup.- or SO.sub.3; M
and M' represent independently from each other a monovalent cation,
for example, an alkali metal ion or an ammonium ion.
[0055] Another type of emulsifiers corresponds to general formula
(IV):
(Y--(R'.sub.f)--Z)M (IV)
wherein Y represents Cl or F or CF2H; R'.sub.f represents a linear
or branched partially fluorinated alkylene having 4 to 10 carbon
atoms; Z represents COO.sup.-, OSO.sub.3.sup.- or SO.sub.3.sup.-; M
represents a monovalent cation, for example, an alkali metal ion or
an ammonium ion.
[0056] The partially fluorinated alkylene means the alkylene
contains at least one unit selected from --CFH--, --CFH.sub.2,
--CF.sub.2H or --CH.sub.2-- units or combinations thereof, but the
alkylene may otherwise be perfluorinated or not fluorinated. The
alkylene may comprise repeating units derived from the monomers
employed in the polymerization.
[0057] Fluorinated emulsifiers corresponding to the general formula
(III) and (IV) are typically generated in situ during the
polymerization for example by recombination or by incomplete
polymerization. In particular, these emulsifiers may be generated
in situ in the preparation of fluoroelastomers by aqueous emulsions
or by suspension and solvent polymerization.
[0058] Generally, the fluorinated emulsifiers according to formulae
(I), (II), (III) or (IV) are low molecular weight compounds, for
example compounds having a molecular weight for the anion part of
the compound of not more than 1000 g/mol, typically not more than
600 g/mol and in particular embodiments, the anion of the
fluorinated carboxylic acid may have a molecular weight of not more
than 500 g/mol.
[0059] The aqueous phase may contain at least 10 ppm, at least 20
ppm, at least 100 ppm, at least 200 ppm, at least 500 or at least
1,000 ppm of an emulsifier according to formula (I), (II), (III) to
(IV).
Particles
[0060] The aqueous phase may also contain particles. The particles
may have an average particle size (number average) of from about 10
or about 50 nm to about 400 nm. Generally, the aqueous phase may
contain from 0.01 to about 10% wt of particles.
Polycationic Polymers and Precursor Polymers Thereof
[0061] The amount of the fluorinated compounds in an aqueous phase
can be significantly reduced by adding thereto at least one
polycationic polymer or a precursor polymer in an effective amount
to cause precipitation of fluorinated compounds.
[0062] The polycationic polymers or precursors thereof may have a
molecular weight (number average (Mn)) of from at least about
5,000, at least about 10,000 g/mol, at least about 50,000 g/mol or
at least about 500,000 g/mol.
[0063] Suitable precursor polymers of the polycationic polymers are
polymers that upon protonation form cationic groups, such as for
example, polyamines or polyimines. Thus, the polycationic polymers
may be formed in acidic or acidified waste water through
protonation.
[0064] The polycationic polymers or precursor polymers may be
aliphatic or aromatic or both. They may be linear or branched and
may also contain cyclic moieties.
[0065] The polycationic polymers contain cationic groups,
including, for example, protonated amine groups, wherein these
amines may be aliphatic, cyclic or aromatic. These amine groups may
be part of the polymer backbone, or as part of a pending group or
part of a group that is grafted onto the polymer backbone.
Preferably, the polycationic polymer contains
--N.sup.+R.sub.1R.sub.2R.sub.3 groups,
--R.sub.4N.sup.+R.sub.5R.sub.6 groups or combinations thereof in
which R.sub.1, R.sub.2, R.sub.3 represent independently from each
other hydrogens or linear, branched or cyclic, saturated or
non-saturated carbohydrates, such as alkyl, aryl or alkaryl
residues. R.sub.4 and R.sub.5 are part of an aliphatic or aromatic
ring that forms with the nitrogen atom a cyclic amine or an
N-hetero aromatic group. R.sub.6 may be hydrogen or a linear,
cyclic, aliphatic or aromatic carbohydrate, such as an alkyl, aryl
or alkaryl residue. Typical examples of cationic groups include
trialkylammonium, dialkylbenzyl ammonium, or pyridinium groups.
[0066] The precursor polymers may contain the groups that upon
protonation form the cationic groups described above.
[0067] The polymers may be copolymers comprising repeating units
derived from polyethylene, acrylamide and/or acrylamide
derivatives, such as, methacrylamides etc. The polymers may also be
or comprise cationically modified starches, that is, starches that
have been chemically modified to contain cationic residues as
described above.
[0068] Suitable polyamines or polyimines include, for example,
polyethylene imines (for example, LUPASOL SK, LUPASOL P from BASF;
Ludwigshafen) and polyamines (for example, ZETAG 7197, CIBA
Speciality Chemicals, Bradford, UK). Suitable examples of
polycationic polymers include ammonium group containing polymers
such as cationic acrylamide copolymers (ZETAG 8816, 8818, ZETAG
8846 FS, ZETAG 8868 FS, from CIBA Speciality Chemicals, Bradford,
UK or PRAESTOL K, E or BC series from Ashland, Krefeld, Germany),
poly(diallyldimethyl ammonium chloride) (PDADMAC, commercially
available as POLYQUAT from Katpol Chemie GmbH, Bitterfeld, Germany
or Aldrich, Munich, Germany) or copolymers thereof, copolymers of
acrylamide and N-acrylooyloxyethyl-N,N,N-trimethyl ammonium salts
such as P(AAm-co-ADAM, commercially available as PRAESTOL, from
Ashland), polyvinyl benzyl trialkyl ammonium chloride (PVBAC),
poly(methacroyloxyethyl) dimethyl benzoyl ammonium chloride (PMBQ),
methacrylamido propyl trimethyl ammonium chloride and mixtures
thereof or cationic modified starches.
Polyanionic Polymers
[0069] The amount of at least one fluorinated compound in the
aqueous phase can be further reduced by adding thereto at least one
polyanionic polymer.
[0070] The polyanionic polymers may be added simultaneously with
the polycationic polymers or subsequently to it. The polyanionic
polymers may have a molecular weight (number average M.sub.n of
from at least about 5,000, 10,000, 50,000, 100,000, 300,000 or at
least about 500,000 g/mol.
[0071] Preferably, the polyanionic polymer has a molecular weight
(number average) of at least about 100,000 g/mol or at least
200,000 g/mol. The polymers may have an average molecular weight
(M.sub.n) of up to about 2 or up to about 5 million g/mol.
[0072] Anionic groups may include, for example, carboxylate groups,
sulphate groups, sulfonate groups, phosphate groups, phosphonate
groups or combinations thereof.
[0073] Examples of suitable polymers include but are polymers
comprising repeating units derived from acrylic acid or acrylic
acid derivates. The polymers may be homo or copolymers.
[0074] Typical examples are copolymers of acrylic acid and
acrylamides (commercially available as PRAESTOL from Ashland,
Krefeld Germany or MAGNAFLOC 90 L-120 L, available from Ciba
Speciality Chemicals, Basel, CH), poly styrene sulfonic acids, poly
2-acrylamido-2-methyl propane sulfonic acids.
Process of Removing Fluorinated Compounds from an Aqueous Phase
[0075] The process of removing fluorinated compounds from an
aqueous phase may involve providing an aqueous phase originating
from the preparation or purification of fluoropolymers by
polymerizing fluorinated monomers in an aqueous medium. The process
may further comprise adding at least one polycationic polymer to
the aqueous phase.
[0076] The polymers are added in an effective amount to initiate
precipitation. It may be continued to be added after the
precipitation has started. The most effective amounts of polymers
depend on the type of the aqueous phase, the pH of the aqueous
phase and the type of polymer (for example, charge density of the
polymer-number of cationic groups and molecular weight) and can be
optimised by routine experimentation of one skilled in the art.
Typically, at least 0.01 mg or at least 0.1 mg of polymer per ppm
of organic bound F are employed. Typical amounts range from about
0.01 to about 50 mg (or from about 0.05 to about 5 mg of polymer)
per ppm of organic bound F in the aqueous phase.
[0077] The polymers may be added as aqueous solutions, dispersions,
emulsions or as solids. They may be added at once, continuously or
at intervals.
[0078] The process may further comprise adding at least one
polyanionic polymer to the waste water. The polyanionic polymers
may be added during or after the addition of the polycationic
polymer. Preferably, the polyanionic polymer is added after the
polycationic polymer has been added, preferably after a precipitate
has formed.
[0079] The polyanionic polymers are added in an effective amount to
increase precipitation. The most effective amounts depend on the
type of aqueous phase, the pH of the waste water and the type of
cationic polymer (for example, charge density of the polymer-number
of cationic groups and molecular weight) and the type of
polyanionic polymers (for example, charge density of the
polyanionic polymer) and can be optimised by routine
experimentation of one skilled in the art. Typically, the weight
ratio of polyanionic polymer to polycationic polymer may be from
about 1 to 100 or from about 10 to 100.
[0080] The precipitation may be aided by the addition of inorganic
salts, by reducing the operating temperatures or by increasing
operating pressures. Generally, the process may be carried out at
ambient temperature and pressure.
[0081] The precipitate can be removed by conventional techniques
including, for example, sedimentation, centrifugation and/or
filtration.
Recovering Fluorinated Compounds from the Precipitate
[0082] The fluorinated compounds may be recovered from the
precipitate, which is another advantage of the process described
herein. For example, fluorinated emulsifiers and/or fluorinated low
molecular weight oligomers may be recovered and recycled for
further use in polymerizations.
[0083] For example, the precipitate, which typically may comprise
the flocculants (polycationic and/or polyanionic polymers),
fluorinated emulsifiers, fluorinated oligomers and polymer
particles may be treated with strong acids, such as, for example,
HF, HCl, H.sub.3PO.sub.4, H.sub.2SO.sub.4, HNO.sub.3, chromic acid,
organic acids or a combination thereof. The acids are typically
added in an amount sufficient to generate a pH of less than about
4, preferably less than about 2. Sulfate-terminated oligomers will
be hydrolyzed under these conditions and the generated alcohols
and/or carboxylic acids can be removed by distillation, preferably
steam distillation, at ambient or reduced pressure. Fluorinated
emulsifiers may also be separated from the precipitate in this way.
Alternatively, or in addition to it, alcohols may be added to the
acidic reaction mixture upon which the carboxylic acids may be
converted into esters. Generally, alcohols such as methanol
ethanol, propanol, isopropanol or another aliphatic or aromatic of
from 4, 5, 6 or 7 and up to 20 C-atoms may be used for this
purpose. The esters formed by the reaction can be phase-separated
or distilled off. Alternatively, fluorinated emulsifiers, oligomers
and/or polymers may be recovered from the acidified precipitate by
extraction using suitable solvents, such as, for example,
hydrofluoroethers (HFE from 3M, St. Paul, Minn., USA) ethers
ketones or acetates or using super critical media, such as super
critical CO.sub.2.
[0084] Therefore, the process may additionally involve: [0085]
treating the precipitate with acids to adjusting the pH of the
precipitate to a pH of less than about 4; [0086] removing
alcohol-terminated fluorinated compounds by distillation or
extraction.
[0087] The process may further involve: [0088] treating the
precipitate with acids to adjusting the pH of the precipitate to a
pH of less than about 4 and (simultaneously or subsequently) adding
an aliphatic or aromatic alcohol; [0089] removing the formed esters
from the precipitate, for example by distillation or
extraction.
[0090] The following examples illustrate the invention further
without the intention to limit the invention thereto.
Test Methods
Particle Sizes
[0091] The size of the particles in the waste water may be
determined by dynamic light scattering using a Malvern Zetazizer
1000 HAS according to ISO/DIS 13321. The measurements were made at
25.degree. C.
Solid Content
[0092] The solid content was determined by subjecting a 10 ml
sample of the waste water to a temperature of 250.degree. C. for 30
minutes and weighing the residue. The solid content of the total
sample was then calculated (according to ISO 12086).
Fluorinated Emulsifier Content
[0093] The content of fluorinated emulsifiers can be measured by
gas chromatography (head space), by converting the emulsifiers into
the corresponding methyl esters (using sulfuric acid and methanol)
and using the methyl ester of perfluorododecanoic acid as internal
standard.
Determination of Total Organic Fluorine (TOF)
[0094] For the determination of the total organic fluoride content
an aliquot of the sample (sample 1) was analysed by
fluoride-sensitive electrodes according to DIN 38405-D4. Another
aliquot of the sample (sample 2) was subjected to Wickbold
combustion and subsequently analysed for F-content by
fluoride-sensitive electrodes. TOF was calculated by subtracting
the F-content of sample 1 from sample 2.
F-Determination with F-Electrodes:
[0095] A known amount of sample was introduced into a 100 ml
plastic cylinder and filled up with water to 25 ml. 25 ml of TISAB
buffer was added. The pH of the solution was controlled to be at
5.5 using a pH-electrode. If necessary the pH was adjusted by
adding 8 molar NaOH.
[0096] The F-content in the adsorption solution was determined
using a fluoride electrode at a pH between 5 and 6 (Orion Ionometer
EA 640, Orion F-electrode 90-02, Orion reference-electrode 94-09
SC, from Thermo-Fisher Scientific Inc, Waltham, Mass., USA).
[0097] The TISAB-solution was prepared by combining 500 mL H2O, 57
ml glacial acetic acid, 58 g NaCl and 5 g 1,2-diamino cyclohexane
tetraacetic acid (IDRANAL IV) and adjusting the pH to 5.5 using 8
molar NaOH and a pH-electrode (Orion pH Electrode 9156 SC from
Thermo Fisher Scientific Inc, Waltham, Mass., USA).
Wickbold Combustion:
[0098] An aliquot of the fluorine-containing sample was introduced
into a quarz glass container and the weight of the sample was
determined. 100 mL of water was filled into the absorption
reservoir of the incinerator (Wickbold Heraeus W4, Heraeus
Quarzglass GmbH, Kleinostheim, Germany). After combustion of the
sample the absorption solution was transferred into a measuring
cylinder and filled up with water to 250 ml.
[0099] Aliquots were transferred into a 100 ml plastic measuring
cylinder and filled with H2O to 25 ml. 25 ml of a TISAB buffer was
added and the F-content of this solution were subjected to
F-determination with the F-electrode as described above.
Materials
[0100] MAGNAFOC 90 L: polyanionic polyacrylamide, medium molecular
weight range, low charge density, from Ciba Speciality Chemicals,
Basel, Switzerland; MAGNAFLOC 110 L: polyanionic polyacrylamide,
medium molecular weight range, medium charge density from Ciba
Speciality Chemicals, Basel, Switzerland; LUPASOL P: polyethylene
imine, molecular weight about 750,000 g/mol, charge density 20
meq/g from BASF, Ludwigshafen, Germany; ZETAG 8818 polycationic
polyacrylamide, very high molecular weight range, high charge
density from Ciba Speciality Chemicals, Basel, Switzerland;
PDADMAC: poly diallydimethyl ammonium chloride, molecular weight
range of 200,000 to 350,000 g/mol, high charge density, from
Aldrich, Munich, Germany.
EXAMPLES
Example 1
APFO Removal by Precipitation
[0101] 1.2 ml of an aqueous solution of Lupasol P (BASF) (0.1% wt)
was added under gentle agitation to 100 ml of APFO solution
(containing 95 ppm APFO) at a pH of about 7 giving an aqueous phase
of 101.2 ml from which a precipitate was formed. The precipitate
was removed after 30 minutes by filtration through a filtering
device (pore size 0.2 .mu.m). The filtered solution had an APFO
concentration of 16 ppm; efficiency rate of APFO removal was
.about.83%.
Example 2
APFO Removal by Precipitation
[0102] Various amounts of the flocculants shown in the table below
were added under gentle agitation to 100 ml of APFO solution
(containing the amount of APFO as indicated in the table below) at
a pH of about 7. The resulting precipitate was removed from the
aqueous phase after 30 minutes by filtration through a filtering
device (pore size 0.2 .mu.m). The APFO content and the efficiency
rate of APFO are also shown in the table below.
TABLE-US-00001 APFO starting Amount of Final APFO- concentration
flocculant concentration Efficiency (ppm) Flocculant (mg) (mg) (%)
95 ZETAG 8818 23.9 3 96 380 PDADMAC 190 2 99 380 PDADMAC 19 51 86 3
PDADMAC 0.3 0.5 83 410 PDADMAC 82 1 99
Example 3
Recycling of APFO
[0103] 6 kg of an aqueous solution containing 0.35% wt APFO were
treated with 30 g of an aqueous solution containing 20.0% wt
PDADMAC. 17 g of APFO were removed by precipitation. The
precipitate was added to a mixture of 200 ml MeOH, 100 ml H.sub.2O
and 10 ml conc. H.sub.2SO.sub.4; the whole reaction mixture was
treated under reflux conditions and after 2 hours the formed ester
was distilled off 16.5 g of the perfluoro octanoic methyl ester
were recovered. The methyl ester was converted into the ammonia
salt by adding aqueous ammonia and simultaneously distilling of
water/methanol.
Example 4
Waste Water from the Preparation of a Fluoroelastomer
[0104] A polymerization kettle with a total volume of 49 L equipped
with an impeller agitator was charged with 29.0 L deionized water,
63 g aqueous ammonia solution (25%), and 40 g diethyl malonate. The
oxygen-free kettle was then heated to 73.degree. C. and the
agitation system was set to 240 rpm. The kettle was charged with
HFP to 6.6 bar absolute, then with VDF to 10.9 bar absolute and
with TFE to 12.0 bar absolute reaction pressure. The polymerization
was initiated by the addition of 240 g 25% wt aqueous ammonium
peroxodisulfate solution. As the reaction started, the reaction
pressure of 12.0 bar absolute was maintained by feeding TFE, VDF
and HFP into the gas phase with feeding ratios of HFP(kg)/TFE(kg)
of 1.285 and of VDF(kg)/TFE(kg) of 1.831. The reaction temperature
of 73.degree. C. was also maintained. After 5 h 3.43 kg of TFE were
fed and the monomer valves were shut. Within 30 minutes the
reaction pressure was down to 3.5 bar. The reactor was vented and
flushed with nitrogen in three cycles.
[0105] The thus obtained polymer dispersion (44.2 kg) had a solid
content of 34.5%. The latex particle diameter was 320 nm according
to dynamic light scattering.
[0106] 1 L of the dispersion was treated with 250 ml of a 4% wt.
aqueous MgCl.sub.2 solution under stirring upon which the
fluoropolymers coagulated. The obtained solid was washed with 2.5 L
of hot (65.degree. C.) and 2.5 L of cold water. The aqueous phases
were collected. The combined aqueous phases contained 570 .mu.g/g
chloride and 190 .mu.g/g magnesium. The chloride content was
determined by ion chromatography (DIN ISO 10304/1 1995). Magnesium
was determined by ICP-OES according to DIN ISO 11885-E22. The
analysis of the sample using a fluoride selective electrode (with
and without Wickbold incineration) gave a content of organic
fluorine (TOF) of 65 .mu.g/g.
Example 5
Reducing the Amount of Fluorinated Compounds from Waste Water
[0107] 300 g of the aqueous phase (waste water) obtained in example
3 were treated under stirring with 71.9 g of an aqueous solution
containing 0.1% wt. of ZETAG 8818. The mixture was stirred for 40
minutes. Small particles were generated which slowly precipitated.
The mixture contained 65 .mu.g/g of organic fluoride (TOF) and was
divided into 3 equal portions.
[0108] Portion 1 was filtered without further treatment. The
content of organic bonded fluorine was reduced from 65 .mu.g/g to
49 .mu.g/g (-25%).
[0109] Portion 2 was treated with 9.1 g of 0.1 wt % aqueous
solution of Magnafloc 110 L under stirring and stirred for 40
minutes. The filtered solution contained 44 .mu.g/g of organic
bonded fluorine (-33%).
[0110] Portion 3 was treated with 28.5 g of 0.1 wt % aqueous
solution of Magnafloc 90 L under stirring and stirred for 40
minutes. The filtered solution contained 39 .mu.g/g of organic
bonded fluorine (-40%).
Example 6 (Comparative)
Removal of Fluorinated Compounds by Anion-Exchange
[0111] A sample of the aqueous phase (waste water) obtained in
example 3 (treated with 150 ppm GENAPOL.times.080 to avoid
clogging) was pumped over a column (9 cm.times.40 cm.sup.2)
containing AMBERJET 4200Cl at a flow rate of 430 mL/h. The volume
of the bed was 350 mL. After 70 L and 200 L of the waste water had
flowed through the column, samples were taken and the content of
fluorinated organic compounds analyzed. The TOF at an eluted volume
of 70 L was 41 .mu.g/g (-38%), and at an eluted volume of 200 L 44
.mu.g/g (-32%).
* * * * *